1. Technical Field
The invention broadly relates to data processing systems. The invention has particular application in a multitasking pen computer system in which a user enters hand printed character and symbols using a stylus to be interpreted as text and gesture commands.
2. Description of the Prior Art
Pen computers are a class of computers that employ a stylus and sensor as an input device. A pen software subsystem, executing as an adjunct to the operating system, processes pen input for the purposes of recognizing stylus input as mouse input commands, hand printed characters (text) or hand printed symbols known as gestures.
The pen subsystem of the OS/2 operating system permits users to write characters directly into a graphical user interface (GUI) window that are subsequently sent to a gesture and handwriting recognition engine for recognition. By default, the system treats the hand printed shapes as gestures unless the window is one that accepts text, such as an edit field or a text entry window. A key requirement of the pen operating system is to facilitate pen input into all applications that are executed by the user, most of which are unaware of the presence of the stylus and the function rich programming interface provided by the pen subsystem. To implement ease of use and good human factors, it is incumbent upon the pen subsystem to make these pen-unaware applications look and feel, from a user interface point of view, like the applications that are pen-aware and take advantage of the pen functionality.
A problem facing users of pen-based computers is applications often display windows that solicit the user to input a large number of various parameters. Good human factors dictate that the application query as much information as possible without requiring the user to navigate multiple windows, so several input fields are painted into the main application window. Given that the user will input via a keyboard or mouse, the sizes of the fields are dictated solely by aesthetics and the legibility of the character fonts. When using a stylus, however, these numerous small windows make handwriting input difficult at best.
Unlike keyboard and mouse applications, when designing pen-based applications, good human factors dictate that the graphical user interface generally emulate pen and paper. That implies that the user be permitted to enter handwritten text directly into the target input fields. Whereas a pen application developer would allow for larger input windows to facilitate handwriting input, many existing applications do not. Therefore a key objective of the pen operating systems is to allow pen input in existing applications written specifically for the keyboard and mouse.
To unconstrain the user, the user must be allowed to write outside the targeted input window. This is highly desirable in that the user is unencumbered and may write in his own natural style. However, once the user begins to write into an entry field, a mode is entered in which all handwriting input is directed to that particular entry field, regardless of where on the display it is written. This precludes the user from progressing easily to another entry field. In order to direct handwriting input into the next field, the user must terminate the current writing mode, which requires the user to either, 1) stop writing for 3 seconds or, 2) to lift the stylus out of the proximity region of the digitizing sensor. While these actions may not seem overly burdensome, they have a debilitating effect on the user interface.
In existing pen operating systems, the user is given a certain amount of area around the entry field into which the user may extend the handwriting. For example, the allowable area may extend 1/2 inch above and below the field. Any stroke that starts outside this field is either ignored or terminates the current mode of collecting strokes. There is no indication of where the writing boundaries are. The user gets a rough idea of the boundary because the system clips the ink to the allowable writing area. But the human factors are not good because the user becomes concerned with squeezing the strokes into an allotted area that cannot be seen. In addition, the fact that strokes outside the area are not painted leaves the user unsure of the actual shape and size of the characters. This causes handwriting recognition accuracy to suffer accordingly.
Further information on these operations may be in U.S. Pat. No. 5,252,951 by Alan Tannenbaum et al entitled "Graphical User Interface with Gesture Recognition in a Multi-Application Environment", assigned to the IBM Corporation and incorporated herein by reference.
Also disclosed is IBM Technical Disclosure Bulletin, Vol. 38 No. 09, Pages 461-62, September 1995, entitled, "Data Interpretation Techniques for a Pen-based Computer" and incorporated herein by reference.
Also disclosed is U.S. Pat. No. 5,404,458 by John M. Zetts entitled, "Recognizing the Cessation of Motion of a Pointing Device on a Display By Comparing a Group of Signals to an Anchor Point" and incorporated herein by reference.
It is therefore an object of the present invention unconstrain the user by allowing the user to write outside the targeted input field.
It is a further object of the present invention to aid the user by providing a visual prompt to indicate the area in which all strokes must start.
It is a further object of the present invention to constrain only the touchdown or first point of each stroke while allowing the user to extend strokes beyond the bounds of the visual prompt, so as not to hinder the user's natural writing.
It is a further object of the present invention to enable the user to start writing immediately in other fields.